JP3772065B2 - Electron gun and cathode ray tube using this electron gun - Google Patents

Electron gun and cathode ray tube using this electron gun Download PDF

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Publication number
JP3772065B2
JP3772065B2 JP2000062969A JP2000062969A JP3772065B2 JP 3772065 B2 JP3772065 B2 JP 3772065B2 JP 2000062969 A JP2000062969 A JP 2000062969A JP 2000062969 A JP2000062969 A JP 2000062969A JP 3772065 B2 JP3772065 B2 JP 3772065B2
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electrode
electron gun
last
focus
electron beam
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JP2000277033A (en
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徳成 朴
尚均 金
奉旭 鄭
哲植 趙
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Samsung SDI Co Ltd
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Samsung SDI Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/48—Electron guns
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/48—Electron guns
    • H01J29/488—Schematic arrangements of the electrodes for beam forming; Place and form of the elecrodes

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  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は電子銃とこれを用いた陰極線管に係り、より詳細には単色の画像を形成する単色陰極線管とこれに装着される電子銃に関する。
【０００２】
【従来の技術】
単色の画像を形成する陰極線管、特にプロジェクションテレビジョンに用いられる単色陰極線管は、図６に示したようにスクリーン面１１を有し、このスクリーン面１１の内面に蛍光膜１２が形成されたバルブ１０を含む。そして前記バルブ１０のネック部１３には蛍光膜を励起するための電子ビームを放出する電子銃２０が設けられ、バルブ１０のコーン部には電子銃２０から放出された電子ビームを偏向させるための偏向ヨーク３０が設けられる。
【０００３】
前述したような陰極線管は、前記電子銃２０から放出される電子ビームが偏向ヨーク３０により偏向されて蛍光膜に走査されることによって画像を形成する。
【０００４】
このような画像を形成するための構成を有する陰極線管は、カラー画像を形成するプロジェクターの構成時三つが用いられる。即ち、前記プロジェクターは三つの陰極線管により赤色、緑色、青色の画像を各々形成して投射スクリーンで合成することによってカラー画像を形成する。従って投射スクリーンに投影される画像の解像度と輝度を高めるためには陰極線管の輝度を高めるべきである。なぜなら各陰極線管により形成される画像を視聴者が直接見ることではなく投射レンズを通じてスクリーンに投射して見るので、輝度が低い場合鮮明な画像を視聴できなくなる。前記陰極線管の輝度を高めるためには、電子銃から放出される電子ビームの電流密度を高めるべきであり、電子銃を構成する各電極に相対的に高い電圧を印加して電子レンズを構成すべきである。
【０００５】
図７にはこのような電子銃の一例を示した。
【０００６】
図示したような電子銃は米国特許４,９０４,８９８号に開示されているものであって、熱電子を放出するためのカソード２１、制御電極２２及びスクリーン電極２３と、前記スクリーン電極と隣接して設けられ分割された下部フォーカス電極２４及び上部フォーカス電極２５と、前記上部フォーカス電極２５の端部を取り囲む最後の加速電極２６とを具備する。そして最後の加速電極２６と共にメーンレンズを形成する前記上部フォーカス電極２５は円筒状のベース部２５ａと連結されたカップ形状部を有するが、このカップ形状部は短い円筒状部２５ｂと、前記短い円筒状部２５ｂから延びてベース部２５ａと連結されるテーパ部２５ｃとを具備する。
【０００７】
前述したような従来の電子銃は、最後の加速電極２６と上部フォーカス電極２５に所定の電圧が印加されてメーンレンズを形成する。この過程で前記最後の加速電極２６の内部に位置する上部フォーカス電極２５の端部が円筒状部２５ｂとテーパ部２５ｃよりなっているので、最後の加速電極２６の内周面と上部フォーカス電極２５の外周面との間に対応される面積が縮まり、テーパ部と最後の加速電極２６の内周面との間の間隔が広くなって耐電圧特性が向上する。
【０００８】
しかし、前記のような電子銃は、上部フォーカス電極２５のテーパ部２５ｃの端部に円筒状部２５ｂが形成されているので、対応面積を縮めるには限界がある。また、前記円筒状部２５ｂでは最後の加速電極２６との間隔が従来と同じ状態を維持しているので、上部フォーカス電極２５の外周面と最後の加速電極２６との間での高電圧差によるアーク放電の発生を根本的に解決できない。
【０００９】
【発明が解決しようとする課題】
そこで、本発明は、最後の加速電極と最後のフォーカス電極との間の耐電圧特性を向上させることができ、電子銃のエージング時高圧を印加できるのでエージング時間を縮められる電子銃とこの電子銃を用いた陰極線管を提供することにその目的がある。
【００１０】
【課題を解決するための手段】
前記目的を達成するために本発明の電子銃は、三極部をなすカソード、制御電極及びスクリーン電極と、前記スクリーン電極から順次に設けられて補助レンズを形成する少なくとも一つ以上のフォーカス電極と、前記フォーカス電極中最後のフォーカス電極を取り囲みながら最後のフォーカス電極と主レンズを形成する最後の加速電極を含む電子銃において、前記最後のフォーカス電極が円筒状のベース部と、前記ベース部の端部に一端が前記ベース部の直径より大きい直径の自由端部を有し、最後の加速電極で取り囲まれるテーパ部とを含んでなったことを特徴とする。
【００１１】
本発明において、前記テーパ部は前記ベース部の端部から延びて一体に形成されたり、別に制作されてベース部と結合してなされることができる。そして前記テーパ部のテーパ角度は電子銃の軸と１０度乃至３０度になすようにすることが望ましい。また本発明において、前記制御電極の電子ビーム通過孔部の厚さを制御電極電子ビーム通過孔の直径の１０％以上に形成することが望ましい。
【００１２】
そして本発明に係る陰極線管は、内面に蛍光膜が形成されたスクリーン面を有しネック部を有するファンネル部を具備したバルブと、前記ネック部に装着されることで、三極部なすカソード、制御電極及びスクリーン電極と、前記スクリーン電極から順次に設けられて補助レンズを形成する少なくとも一つ以上のフォーカス電極と、前記フォーカス電極中カソードから最端部に位置するフォーカス電極を取り囲みながらこのフォーカス電極と主レンズを形成する最後の加速電極を具備し、前記フォーカス電極中最後のフォーカス電極が円筒状のベース部と、前記ベース部の端部に一端が前記ベース部の直径より大きい直径の自由端部を有し、最後の加速電極で取り囲まれるテーパ部を含んでなった電子銃と、前記ネック部とファンネル部の境界部に装着されて電子銃から放出される電子ビームを蛍光膜の各部位に偏向させる偏向ヨークとを含んでなったことを特徴とする。
【００１３】
【発明の実施の形態】
以下、添付した図面を参照して本発明に係る電子銃とこの電子銃を用いた陰極線管の望ましい実施の形態を詳細に説明する。
【００１４】
本発明に係る電子銃とこの電子銃を用いた陰極線管、即ち、プロジェクターの赤、青、緑色画像中一つの画像を形成するための陰極線管の一実施の形態を図１に示した。
【００１５】
図示したように、陰極線管はバルブ４０を具備するが、前記内部に蛍光膜４１が形成されたスクリーン面４２とネック部４３ａを有するファンネル部４３とを含む。そして前記ネック部４３ａには前記蛍光膜４１を励起するための電子ビームを放出する電子銃５０が設けられ、前記ファンネル部４３には前記電子銃５０から放出される電子ビームを蛍光膜４１の各部位に走査するための偏向ヨーク６０が設けられる。
【００１６】
前記電子銃５０は、図２に示したように前置三極部をなすカソード５１、制御電極５２及びスクリーン電極５３と、補助レンズをなす少なくとも一つ以上のフォーカス電極５４、５５と、前記フォーカス電極５４、５５中カソード５１から一番遠く離れているフォーカス電極５５(以下、最後のフォーカス電極という)と隣接して設けられて主レンズをなす最後の加速電極５６とを含む。
【００１７】
ここで、前記制御電極５２とスクリーン電極５３は円筒状または板状の電極よりなり、フォーカス電極５４は円筒状よりなされることができる。そして前記最後のフォーカス電極５５は円筒状のベース部５５ａと、前記ベース部５５ａの端部にベース部５５ａの直径より大きい直径の端部を有するテーパ部５５ｂとを含む。前記テーパ部５５ｂはベース部５５ａの端部から延びて一体型に形成でき、別の部材で製作してベース部材５５ａと接合して形成できる。前記テーパ部５５ｂを別の部材で製作して接合する場合には、テーパ部５５ｂの底部(bottom)とベース部５５ａの端部にフランジ部を形成して相互接合することが望ましい。前記テーパ部５５ｂのテーパ角度は電子銃の中心軸に対して１０度乃至３０度をなすようにすることが望ましい。
【００１８】
そして、上記のように最後のフォーカス電極５５に単一のテーパ部５５ｂが形成され主レンズの直径が多少小さくなる場合があるが、これを勘案して図３に示したように前記制御電極５２の電子ビーム通過孔５２Ｈの形成部位の厚さＴを電子ビーム通過孔直径Ｄの１０％以上に形成することが望ましい。
【００１９】
前記最後の加速電極５６は、前記ベース部５５ａの端部とテーパ部５５ｂを取り囲む円筒状に形成されるが、ベース部５５ａ側の端部は最後のフォーカス電極５６の端部の直径より小さな直径で形成される。
【００２０】
そして、前述したように、電子銃を構成する各電極は一対のガラスビード５７により位置固定され、前記各電極はステム７０に支持されたリードピン７１と導電性コネクタ７２により連結される。
【００２１】
前述したように構成された本発明に係る電子銃とこの電子銃を採用した陰極線管は、各電子銃５０のカソード５１と各電極５２〜５６に所定の電圧が印加されることによって電極間、即ちスクリーン電極５３とフォーカス電極５４との間にはプリフォーカスレンズが形成され、前記フォーカス電極５４と最後のフォーカス電極５５との間には補助集束レンズが形成され、前記最後のフォーカス電極５５と最後の加速電極５６との間には主レンズが形成される。
【００２２】
上記のように各電極に電圧を印加して電子レンズを形成する過程で、カソード５１から放出された電子ビームの加速力と集束力を高めるためには、電子レンズを形成する電極間の電圧差を大きくする。例えば、主レンズを形成する最後のフォーカス電極５５と最後の加速電極５６との間の電圧差は２０Ｋｖ以上になるが、この場合高い電圧差により絶縁破壊が起きて最後のフォーカス電極５５と最後の加速電極５６との間にアークが発生する。しかし、前記電子銃の最後のフォーカス電極５５のベース部５５ａにはテーパ部５５ｂが形成されているので、最後の加速電極５６の内周面と最後のフォーカス電極５５の外周面との間に対応される面積を縮めることができてこれら間に絶縁破壊が起きることを防止できる。
【００２３】
特に、前記テーパ部５５ｂのテーパ角度は、電子銃の中心に対して１０度乃至３０度で形成されているので、最後の加速電極５６の内周面とテーパ部５５ｂの端部との間隔が十分に確保される。前記データ部の角度を１０乃至３０度で形成する場合、主レンズの口径が小さくなることによって主レンズの球面収差により電子ビームスポットサイズが多少大きくなる傾向があるが、本発明者のシミュレーションの結果、主レンズの収差は大きく増加せず、電子ビームスポットサイズも中、低電流領域であまり大きくならないことが分かった。
【００２４】
即ち、図４に示したように、最後のフォーカス電極にテーパ部と円筒部が形成された場合、電子ビームスポットのサイズ(グラフＡ)は低電流領域で相対的に大きくなり、高電流領域では多少大きくなることが分かり、最後のフォーカス電極５５にテーパ部５５ｂだけを形成する場合中低電流領域では電子ビームスポットサイズ(グラフＢ)が相対的に小さくなり高電流領域では多少大きくなることが分かった。
【００２５】
そして、最後のフォーカス電極５５に単一のテーパ部５５ｂを形成し、制御電極５２の電子ビーム通過孔５２Ｈの厚さＴを電子ビーム通過孔直径Ｄの１０％以上に形成した場合、図４に示したように低電流領域及び高電流領域で電子ビームスポットのサイズ(図４グラフＣ、図５グラフＥ)が顕著に小さくなることが分かった。本発明者の実験によれば、制御電極５２の電子ビーム通過孔５２Ｈの厚さＴを電子ビーム通過孔直径Ｄの１０％以下にする場合にはむしろ電子ビームスポットのサイズ(図５のグラフＦ)が大きくなることが分かった。このような作用は図３に示したように制御電極５２の厚さＴを厚く形成すれば、カソード５１の電子放出部の縁部から放出された電子ビームＢＥのクロスオーバー点Ｐの位置がカソード５１側に移動してスクリーン電極５３とフォーカス電極５４との間に形成されるプリフォーカスレンズへの電子ビーム入射角が大きくなり、さらには主レンズに入射される電子ビームの入射角が小さくなって電子ビームのスポットサイズが小さくなる。
【００２６】
前述したように、電子レンズが形成された状態で前記カソードから放出された熱電子、即ち電子ビームは各電子レンズを通過しながら集束及び加速されて蛍光膜にランディングされることによって画像を形成する。
【００２７】
【発明の効果】
以上説明したように、本発明の電子銃とこの電子銃を採用した陰極線管は、最後のフォーカス電極と最後の加速電極の高い電圧差による絶縁破壊を防止できるので耐電圧特性を向上させることができ、特に耐電圧特性の向上で高圧エージングが可能でエージングにかかる時間を短縮できる利点を有する。
【００２８】
本発明は図面に示した一実施の形態を参考として説明したが、これは例示的なことに過ぎなく、本技術分野の通常の知識を有する者であればこれより多様な変形及び均等な他の実施の形態ができることを理解するはずである。従って、本発明の真の技術的な保護範囲は特許請求範囲の技術的思想により決まるべきである。
【図面の簡単な説明】
【図１】本発明に係る陰極線管の一部切除斜視図。
【図２】本発明に係る電子銃の一部切除側面図。
【図３】電子銃の三極部を抜粋して示す一部切除斜視図であって、電子ビームの軌跡を可視化して示す図である。
【図４】電流と電子ビームサイズの関係を示すグラフ。
【図５】電流と電子ビームサイズの関係を示すグラフ。
【図６】従来の陰極線管の断面図。
【図７】従来の陰極線管用電子銃を示す一部切除側面図。
【符号の説明】
４０ バルブ
５０ 電子銃
５１ カソード
５５ 最後のフォーカス電極
５６ 最後の加速電極
６０ 偏向ヨーク[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electron gun and a cathode ray tube using the same, and more particularly to a monochromatic cathode ray tube for forming a monochromatic image and an electron gun attached thereto.
[0002]
[Prior art]
A cathode ray tube for forming a monochrome image, particularly a monochrome cathode ray tube used for projection television, has a screen surface 11 as shown in FIG. 6, and a bulb having a fluorescent film 12 formed on the inner surface of the screen surface 11. 10 is included. The neck portion 13 of the bulb 10 is provided with an electron gun 20 that emits an electron beam for exciting the fluorescent film, and the cone portion of the bulb 10 is used for deflecting the electron beam emitted from the electron gun 20. A deflection yoke 30 is provided.
[0003]
The cathode ray tube as described above forms an image by the electron beam emitted from the electron gun 20 being deflected by the deflection yoke 30 and scanned on the fluorescent film.
[0004]
Three cathode ray tubes having a configuration for forming such an image are used when a projector for forming a color image is configured. That is, the projector forms a color image by forming red, green and blue images with three cathode ray tubes and combining them with a projection screen. Therefore, in order to increase the resolution and brightness of the image projected on the projection screen, the brightness of the cathode ray tube should be increased. This is because an image formed by each cathode ray tube is not directly viewed by a viewer but projected onto a screen through a projection lens, so that a clear image cannot be viewed when the luminance is low. In order to increase the luminance of the cathode ray tube, the current density of the electron beam emitted from the electron gun should be increased, and a relatively high voltage is applied to each electrode constituting the electron gun to form the electron lens. Should.
[0005]
FIG. 7 shows an example of such an electron gun.
[0006]
An electron gun as shown is disclosed in U.S. Pat. No. 4,904,898, and is adjacent to the screen electrode, a cathode 21, a control electrode 22 and a screen electrode 23 for emitting thermal electrons. The lower focus electrode 24 and the upper focus electrode 25 which are provided and divided, and the last acceleration electrode 26 surrounding the end of the upper focus electrode 25 are provided. The upper focus electrode 25 that forms a main lens together with the last acceleration electrode 26 has a cup-shaped portion connected to a cylindrical base portion 25a. The cup-shaped portion includes a short cylindrical portion 25b and the short cylindrical portion. A taper portion 25c extending from the shape portion 25b and connected to the base portion 25a.
[0007]
In the conventional electron gun as described above, a predetermined voltage is applied to the last acceleration electrode 26 and the upper focus electrode 25 to form a main lens. In this process, the end portion of the upper focus electrode 25 located inside the last acceleration electrode 26 is composed of the cylindrical portion 25b and the taper portion 25c. The area corresponding to the outer peripheral surface of the first electrode is reduced, the distance between the tapered portion and the inner peripheral surface of the last acceleration electrode 26 is increased, and the withstand voltage characteristics are improved.
[0008]
However, since the electron gun as described above has the cylindrical portion 25b formed at the end of the taper portion 25c of the upper focus electrode 25, there is a limit in reducing the corresponding area. Further, in the cylindrical portion 25b, the distance from the last acceleration electrode 26 is kept the same as the conventional one, so that a high voltage difference between the outer peripheral surface of the upper focus electrode 25 and the last acceleration electrode 26 is caused. The generation of arc discharge cannot be fundamentally solved.
[0009]
[Problems to be solved by the invention]
Accordingly, the present invention can improve the withstand voltage characteristics between the last acceleration electrode and the last focus electrode, and can apply a high voltage during aging of the electron gun, so that the aging time can be shortened and the electron gun It is an object to provide a cathode ray tube using the above.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, an electron gun of the present invention comprises a cathode forming three poles, a control electrode, and a screen electrode, and at least one focus electrode that is sequentially provided from the screen electrode to form an auxiliary lens. An electron gun including a last acceleration electrode that forms a main lens with the last focus electrode while surrounding the last focus electrode in the focus electrode, wherein the last focus electrode has a cylindrical base portion and an end of the base portion The portion includes a tapered portion having a free end portion having a diameter larger than that of the base portion and surrounded by the last acceleration electrode .
[0011]
In the present invention, the tapered portion may be integrally formed extending from the end portion of the base portion, or may be separately manufactured and combined with the base portion. The taper angle of the taper is preferably 10 to 30 degrees with respect to the axis of the electron gun. In the present invention, it is desirable that the thickness of the electron beam passage hole portion of the control electrode is 10% or more of the diameter of the control electrode electron beam passage hole.
[0012]
A cathode ray tube according to the present invention includes a bulb having a screen surface having a fluorescent film formed on the inner surface and a funnel portion having a neck portion, and a cathode that is a triode by being attached to the neck portion, A control electrode and a screen electrode, at least one focus electrode provided in order from the screen electrode to form an auxiliary lens, and the focus electrode surrounding the focus electrode located at the extreme end from the cathode in the focus electrode And the last acceleration electrode forming the main lens, the last focus electrode in the focus electrode being a cylindrical base portion, and a free end having a diameter larger than the diameter of the base portion at one end of the base portion has a section, an electron gun comprise a tapered portion that is surrounded by the end of the accelerating electrode, a boundary of the neck portion and a funnel portion It mounted on the part, characterized in that it includes a deflection yoke for deflecting the electron beams emitted from the electron gun to each part of the fluorescent film.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of an electron gun according to the present invention and a cathode ray tube using the electron gun will be described in detail with reference to the accompanying drawings.
[0014]
FIG. 1 shows an embodiment of an electron gun according to the present invention and a cathode ray tube using the electron gun, that is, a cathode ray tube for forming one of red, blue and green images of a projector.
[0015]
As shown in the figure, the cathode ray tube includes a bulb 40, and includes a screen surface 42 on which a fluorescent film 41 is formed and a funnel portion 43 having a neck portion 43a. The neck portion 43a is provided with an electron gun 50 that emits an electron beam for exciting the fluorescent film 41. The funnel portion 43 receives an electron beam emitted from the electron gun 50 on each of the fluorescent films 41. A deflection yoke 60 is provided for scanning the part.
[0016]
As shown in FIG. 2, the electron gun 50 includes a cathode 51, a control electrode 52, and a screen electrode 53 forming a front triode, at least one focus electrode 54, 55 forming an auxiliary lens, and the focus Among the electrodes 54 and 55, a focus electrode 55 (hereinafter referred to as the last focus electrode) that is farthest from the cathode 51 and a last acceleration electrode 56 that is provided adjacent to each other to form a main lens are included.
[0017]
Here, the control electrode 52 and the screen electrode 53 may be cylindrical or plate electrodes, and the focus electrode 54 may be cylindrical. The last focus electrode 55 includes a cylindrical base portion 55a and a tapered portion 55b having an end portion with a diameter larger than the diameter of the base portion 55a at the end portion of the base portion 55a. The tapered portion 55b extends from the end of the base portion 55a and can be integrally formed, or can be formed of another member and joined to the base member 55a. When the taper portion 55b is manufactured and joined with another member, it is desirable to form a flange portion between the bottom portion of the taper portion 55b and the end portion of the base portion 55a and join them together. It is desirable that the taper angle of the taper portion 55b is 10 to 30 degrees with respect to the central axis of the electron gun.
[0018]
As described above, there is a case where a single taper portion 55b is formed on the last focus electrode 55 and the diameter of the main lens is somewhat reduced. In consideration of this, as shown in FIG. It is desirable that the thickness T of the formation site of the electron beam passage hole 52H be 10% or more of the electron beam passage hole diameter D.
[0019]
The last acceleration electrode 56 is formed in a cylindrical shape surrounding the end portion of the base portion 55 a and the tapered portion 55 b, and the end portion on the base portion 55 a side has a diameter smaller than the diameter of the end portion of the last focus electrode 56. Formed with.
[0020]
As described above, each electrode constituting the electron gun is fixed in position by a pair of glass beads 57, and each electrode is connected by the lead pin 71 supported by the stem 70 and the conductive connector 72.
[0021]
The electron gun according to the present invention configured as described above and a cathode ray tube employing the electron gun are configured such that a predetermined voltage is applied to the cathode 51 of each electron gun 50 and each of the electrodes 52 to 56, That is, a prefocus lens is formed between the screen electrode 53 and the focus electrode 54, and an auxiliary focusing lens is formed between the focus electrode 54 and the last focus electrode 55, and the last focus electrode 55 and the last focus electrode 55 are formed. A main lens is formed between the acceleration electrode 56 and the acceleration electrode 56.
[0022]
In order to increase the accelerating force and focusing force of the electron beam emitted from the cathode 51 in the process of forming the electron lens by applying a voltage to each electrode as described above, the voltage difference between the electrodes forming the electron lens is increased. Increase For example, the voltage difference between the last focus electrode 55 forming the main lens and the last acceleration electrode 56 is 20 Kv or more. In this case, a high voltage difference causes dielectric breakdown, and the last focus electrode 55 and the last acceleration electrode 56 An arc is generated between the acceleration electrode 56 and the electrode. However, since the taper portion 55b is formed in the base portion 55a of the last focus electrode 55 of the electron gun, there is a correspondence between the inner peripheral surface of the last acceleration electrode 56 and the outer peripheral surface of the last focus electrode 55. It is possible to reduce the area to be formed and prevent dielectric breakdown between them.
[0023]
In particular, since the taper angle of the taper portion 55b is 10 degrees to 30 degrees with respect to the center of the electron gun, the distance between the inner peripheral surface of the last acceleration electrode 56 and the end portion of the taper portion 55b is small. Sufficiently secured. When the angle of the data portion is 10 to 30 degrees, the electron beam spot size tends to be slightly increased due to the spherical aberration of the main lens due to a decrease in the diameter of the main lens. It was found that the aberration of the main lens did not increase greatly, and the electron beam spot size did not become so large in the middle and low current region.
[0024]
That is, as shown in FIG. 4, when a tapered portion and a cylindrical portion are formed on the last focus electrode, the size of the electron beam spot (graph A) is relatively large in the low current region, and in the high current region. It can be seen that the electron beam spot size (graph B) is relatively small in the middle and low current region and slightly larger in the high current region when only the tapered portion 55b is formed on the final focus electrode 55. It was.
[0025]
When a single taper portion 55b is formed in the last focus electrode 55 and the thickness T of the electron beam passage hole 52H of the control electrode 52 is formed to be 10% or more of the electron beam passage hole diameter D, FIG. As shown, it was found that the size of the electron beam spot (graphs C and 5 in FIG. 5) was significantly reduced in the low current region and the high current region. According to the experiment by the present inventor, when the thickness T of the electron beam passage hole 52H of the control electrode 52 is set to 10% or less of the electron beam passage hole diameter D, the size of the electron beam spot (the graph F in FIG. 5). ) Became larger. As shown in FIG. 3, if the thickness T of the control electrode 52 is formed thick as shown in FIG. 3, the position of the crossover point P of the electron beam BE emitted from the edge of the electron emission portion of the cathode 51 becomes the cathode. The angle of incidence of the electron beam on the prefocus lens formed between the screen electrode 53 and the focus electrode 54 is increased and the angle of incidence of the electron beam incident on the main lens is reduced. The spot size of the electron beam is reduced.
[0026]
As described above, the thermoelectrons emitted from the cathode in the state in which the electron lens is formed, that is, the electron beam is focused and accelerated while passing through each electron lens and is landed on the fluorescent film to form an image. .
[0027]
【The invention's effect】
As described above, the electron gun of the present invention and the cathode ray tube employing this electron gun can prevent dielectric breakdown due to a high voltage difference between the last focus electrode and the last acceleration electrode, so that the withstand voltage characteristic can be improved. In particular, there is an advantage that high voltage aging is possible by improving the withstand voltage characteristics and the time required for aging can be shortened.
[0028]
The present invention has been described with reference to an embodiment shown in the drawings. However, this is merely an example, and various modifications and equivalents may be made by those having ordinary skill in the art. It should be understood that the following embodiments are possible. Therefore, the true technical protection scope of the present invention should be determined by the technical idea of the claims.
[Brief description of the drawings]
FIG. 1 is a partially cutaway perspective view of a cathode ray tube according to the present invention.
FIG. 2 is a partially cutaway side view of an electron gun according to the present invention.
FIG. 3 is a partially cutaway perspective view showing an excerpt of a triode portion of an electron gun, and is a view showing a trajectory of an electron beam.
FIG. 4 is a graph showing the relationship between current and electron beam size.
FIG. 5 is a graph showing the relationship between current and electron beam size.
FIG. 6 is a sectional view of a conventional cathode ray tube.
FIG. 7 is a partially cutaway side view showing a conventional electron gun for a cathode ray tube.
[Explanation of symbols]
40 valve 50 electron gun 51 cathode 55 last focus electrode 56 last acceleration electrode 60 deflection yoke

Claims (7)

三極部をなすカソード、制御電極及びスクリーン電極と、前記スクリーン電極から順次に設けられて補助レンズを形成する少なくとも一つ以上のフォーカス電極と、前記フォーカス電極中最後のフォーカス電極を取り囲みながら最後のフォーカス電極と主レンズを形成する最後の加速電極を含む電子銃において、
前記最後のフォーカス電極が円筒状のベース部と、前記ベース部の端部に一端が前記ベース部の直径より大きい直径の自由端部を有し、最後の加速電極で取り囲まれるテーパ部とを含んでなったことを特徴とする電子銃。A cathode, a control electrode, and a screen electrode forming a triode, at least one focus electrode that is sequentially provided from the screen electrode to form an auxiliary lens, and a last electrode surrounding the last focus electrode in the focus electrode In the electron gun that includes the focus electrode and the last acceleration electrode that forms the main lens,
The last focus electrode includes a cylindrical base portion, and a tapered portion having a free end portion having a diameter larger than the diameter of the base portion at an end portion of the base portion and surrounded by the last acceleration electrode. An electron gun characterized by 前記テーパ部は前記ベース部の端部から延びて一体に形成されたことを特徴とする請求項１に記載の電子銃。  The electron gun according to claim 1, wherein the tapered portion extends integrally from an end portion of the base portion. 前記テーパ部のテーパ角度が電子銃の中心軸に対して１０度乃至３０度よりなっていることを特徴とする請求項１に記載の電子銃。  The electron gun according to claim 1, wherein a taper angle of the taper portion is 10 degrees to 30 degrees with respect to a central axis of the electron gun. 前記制御電極の電子ビーム通過孔部位の厚さが制御電極電子ビーム通過孔の直径の１０％以上であることを特徴とする請求項１に記載の電子銃。  2. The electron gun according to claim 1, wherein the thickness of the electron beam passage hole portion of the control electrode is 10% or more of the diameter of the control electrode electron beam passage hole. 内面に蛍光膜が形成されたスクリーン面を有しネック部を有するファンネル部を具備したバルブと、
前記ネック部に装着されることで、三極部をなすカソード、制御電極及びスクリーン電極と、前記スクリーン電極から順次に設けられて補助レンズを形成する少なくとも一つ以上のフォーカス電極と、前記フォーカス電極中カソードから最端部に位置したフォーカス電極を取り囲みながらこのフォーカス電極と主レンズを形成する最後の加速電極を具備し、前記最後のフォーカス電極が円筒状のベース部と、前記ベース部の端部に一端が前記ベース部の直径より大きい直径の自由端部を有し、最後の加速電極で取り囲まれるテーパ部を含んでなった電子銃と、
前記ネック部とファンネル部の境界部に装着されて電子銃から放出される電子ビームを蛍光膜の各部位に偏向させる偏向ヨークと、
を含んでなったことを特徴とする陰極線管。A bulb having a screen surface having a fluorescent film formed on the inner surface and a funnel portion having a neck portion;
A cathode, a control electrode, and a screen electrode forming a triode by being attached to the neck portion, at least one focus electrode that is sequentially provided from the screen electrode to form an auxiliary lens, and the focus electrode A final acceleration electrode is formed to form a focus lens and a main lens while surrounding the focus electrode located at the extreme end from the middle cathode, the last focus electrode being a cylindrical base portion, and an end portion of the base portion An electron gun having a free end portion having a diameter larger than that of the base portion and including a tapered portion surrounded by the last acceleration electrode ;
A deflection yoke that is attached to the boundary between the neck portion and the funnel portion and deflects the electron beam emitted from the electron gun to each part of the fluorescent film;
A cathode ray tube comprising: 前記テーパ部のテーパ角度が電子銃の中心軸に対して１０度乃至３０度よりなっていることを特徴とする請求項５に記載の陰極線管。  6. The cathode ray tube according to claim 5, wherein a taper angle of the taper portion is 10 degrees to 30 degrees with respect to a central axis of the electron gun. 前記制御電極の電子ビーム通過孔部位の厚さが制御電極電子ビーム通過孔の直径の１０％以上であることを特徴とする請求項５に記載の陰極線管。  6. The cathode ray tube according to claim 5, wherein the thickness of the electron beam passage hole portion of the control electrode is 10% or more of the diameter of the control electrode electron beam passage hole.
JP2000062969A 1999-03-11 2000-03-08 Electron gun and cathode ray tube using this electron gun Expired - Fee Related JP3772065B2 (en)

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